1. Field of the Invention
This invention is in the field of thermally powered heat transfer systems.
In particular, the invention is an improvement to and an extension of the Thermally Powered Engine by Robert W. Clark, Jr., application Ser. No. 803,549 filed on Dec. 2, 1985, now U.S. Pat. No. 4,617,801.
2. Description of the Prior Art
The thermally powered engine disclosed in the aforementioned application comprises one or more pairs of power cylinders, each power cylinder having associated with it a powered cylinder for converting thermal energy into useful heating, cooling, or mechanical work. Each of the power cylinders has a piston reciprocally mounted within, with each piston being rigidly connected to a piston mounted within the associated powered cylinder. Each of the pistons in the power cylinders divides its respective power cylinder into two portions, typically an upper and lower portion. A flexible diaphragm is mounted in the lower interior space or portion of each power cylinder. The space enclosed between the diaphragm and the lower end of the cylinder defines a power chamber. The power chambers of each pair of power cylinders are part of a closed heat transfer loop which includes a working fluid, an evaporator, and a condenser. The difference in temperature between the evaporator and the condenser produces a pressure differential between the evaporator and the condenser, and this pressure differential is used to exert a force on one of the power pistons. In addition, the upper portion of each power cylinder is filled with a second fluid. Connecting means is provided for connecting the upper portions of the power cylinders together, to allow the second, or control, fluid to act as a liquid piston, traveling between, or coupling, the two cylinders. Thus, when a piston in one of the power cylinders travels upwardly, the second, or control fluid in the upper portion of that cylinder is forced into the upper portion of the adjacent cylinder, which in turn causes the piston in the adjacent cylinder to travel downwardly. Thus, the pistons in the two power chambers move substantially 180.degree. out of phase with one another. The downward motion of one of the pistons causes the diaphragm in the lower portion of the cylinder for that piston to flex downwardly, which in turn activates a switch for controlling electrically powered solenoid valves to regulate the flow of the working fluid into and out of the power chambers of the working fluid in the closed heat transfer loop. Each change in position of the valves causes a change in the flow path of the working fluid in the heat transfer loop, which in turn causes the pistons to alternately reciprocate and to generate power in a cyclical manner.
The aforementioned thermal engine is capable of utilizing a relatively small temperature difference to perform a number of useful functions, such as heating water for a home, powering a refrigeration system or a heat pump, acting as a compressor for compressing gas, pumping liquids, or performing other kinds of mechanical work. A major advantage of this system is that it can be powered by naturally occurring temperature differences, by solar energy, or by any fuel including biomass.
One drawback of the aforementioned thermal engine, however, is that a certain amount of electrical energy is required to power the solenoid valves which control the flow of the working fluid in the closed heat transfer loop into and out of the power chambers. Because the engine requires an electrical power source independent of the engines, it can not be easily utilized in developing nations or in other remote areas of the world where electric power is not readily available.
A need therefore exists for a thermally powered engine which is not dependent on a source of electric power.